Babesia spp. in questing ticks from eastern Poland: prevalence and species diversity.

A total of 853 questing Ixodes ricinus males, females, and nymphs and of 582 questing Dermacentor reticulatus males and females were collected from vegetation on the territory of the Lublin province (eastern Poland). The ticks were examined for the presence of Babesia by PCR detecting part of 18S ribosomal RNA (rRNA) gene and nuclear small subunit rRNA (SS-rDNA) for determining of Babesia spp. and Babesia microti, respectively. The overall incidence of Babesia strains in I. ricinus ticks was 4.6%. Three species of Babesia were identified. The prevalent species was B. microti which occurred in 2.8% of ticks, while Babesia venatorum, Babesia divergens, and unidentified Babesia species were found at the frequency of 1.2, 0.2, and 0.3%, respectively. Altogether, B. microti constituted 61.5% of the total strains detected in I. ricinus, B. venatorum-25.7%, B. divergens-5.1%, and unidentified Babesia species-7.7%. The prevalence of Babesia species in I. ricinus did not depend significantly on locality (χ(2) = 1.885, P = 0.390) nor on the tick stage (χ(2) = 4.874, P = 0.087). The incidence of Babesia strains in D. reticulatus ticks was 2.7%. Two species of Babesia were identified. Again, the prevalent species was B. microti which occurred in 2.1% of ticks, while B. canis was found in 0.7% of ticks. In one D. reticulatus female, B. canis and B. microti co-infection was found. Altogether, B. microti constituted 75% of the total strains detected in D. reticulatus while B. canis formed 25% of the total strains. The frequency of the occurrence of Babesia species in D. reticulatus did not depend significantly on locality (χ(2) = 0.463, P = 0.793). The difference between the prevalence of Babesia in males and females of D. reticulatus was insignificant (P = 0.0954); nymphs were not found. The dominance of B. microti in the species composition of tick-borne Babesia found in this study was typical for eastern Europe. In conclusion, the results revealed that the population inhabiting the forested area of eastern Poland could be exposed to Babesia parasites, especially to those from the species B. microti, by a bite of I. ricinus, a competent vector of human babesiosis, and probably also by a bite of D. reticulatus whose role in the transmission of human babesiosis needs to be clarified.